In the automotive Original Equipment Manufacturer (O.E.M.) industry, it is an accepted, guiding principle that appearance and styling sells automobiles and vehicles. When purchasing a vehicle, appearance and styling are as important to the consumer as are other vehicle characteristics such as safety, performance and fuel economy.
One of the most important characteristics of an automobile's appearance and styling is the paint finish. Improvements in automotive paints and paint processes have resulted in O.E.M.s using almost exclusively "high-tech" glamour finishes such as basecoat/clear topcoat coatings which consist of a thin, pigmented, inner base coat and a thicker clear outer top coat. These "high-tech" finishes have improved depth, gloss, distinctness of image, chromaticity and durability.
The importance of the coating process for both appearance and corrosion protection is evidenced by the fact that approximately 40% to 50% of the cost of building an automobile is attributable to the cost of the coatings and the coating application process. In addition, the coating process takes up approximately 40% of the floor space in an O.E.M. assembly plant.
There is a need in the automotive industry to move the coating operation out of the OEM assembly plant. There are numerous reasons why it is not desirable to have a coating operation in an OEM plant. First of all, the present OEM coating operations are extremely inefficient. It is estimated that about 50% of the coatings are wasted as overspray during the coating process. Massive, costly environmental controls are necessary to capture the overspray. The cost of the wasted overspray paint and the costs attributable to the required environmental controls add considerably to the OEM's overhead.
Secondly, an OEM assembly plant is essentially a mechanical assembly operation, while the coating operations are in essence physico-chemical processes. The efficiency of the assembly process could be greatly enhanced by moving the coating process outside of the assembly plant.
Thirdly, it is known that dust and particles adversely affect coatings, both in appearance and integrity. Since the nature of an OEM assembly plant is mechanical assembly requiring an large open facility, it is difficult to control the environment us such a plant to completely eliminate dust and particles. There is a need to conduct coating operations in a controlled environment wherein the process takes place in a contained area with state-of-the-art heating, ventilating, air-conditioning, and filtration utilities, and environmental controls.
Environmental concerns as previously mentioned are yet another reason for moving the coating operation outside of the OEM assembly plant. The typical OEM coating and curing operations generate significant emissions of volatile organic compounds (VOC) into the environment, both within and outside of the OEM assembly plant. Along with the VOC emissions, significant quantities of waste are generated by the coating processes. This waste must be disposed of in strict compliance with all applicable federal, state and local environmental regulations at considerable cost.
Automobile manufacturers would prefer that automobile bodies painted are "off-site" and shipped to the assembly plant. While it is theoretically possible to coat the automobile bodies at the off-site manufacturing facility, this has not been possible due to the likelihood of damage to the finishes that would almost certainly occur during shipping.
In addition to the problem associated with in-plant coating operations, another problem facing OEM assembly plants is the coating of plastic bodies. There is a movement in the industry to convert from carbon steel to plastic bodied cars., Plastic parts are difficult to coat due to the inherent nature of plastics, which typically have difficult to adhere to surfaces. Plastics are also susceptible to attack and degradation from the solvents that are typically contained in automotive paints. Plastics are typically heat sensitive and require low temperature cure coatings. However, low temperature coatings do not always have optimal coating properties such as durability, gloss and solvent resistance. In addition, it is difficult to produce an automotive quality "glamour" finish on a plastic body part due to the inherent surface distortions and imperfections associated with molded body parts. In order to compensate for surface defects, primers and primer/surfaces must be used on plastic parts, not for corrosion protection, but to mask surface defects. In addition to plastic bodies, alternative substitute materials such as cellulosic materials and ceramic materials as well as other available materials are under consideration for use in automobile bodies.
There have been attempts to move a coating process out of assembly plants. U.S. Pat. No. 2,331,546 discloses a method of coating a flat steel plate with a flexible automotive coating. The coated plates are then die-formed into automobile body parts which can be directly assembled into an automobile body, purportedly without requiring any additional finishing treatment.
U.S. Pat. No. 3,774,428 discloses a method of precoating coiled aluminum metal and subjecting the metal to a die process to create a surface pattern. The resulting die-formed coated articles are used as siding for buildings.
U.S. Pat. No. 4,769,100 discloses a method of applying carrier films prepainted with metallic paint to automobile body panels. While such prepainted free films have the advantage of application over flexible substrates, they are subject to certain disadvantages. Such films tend to trap bubbles during application to the substrate; they also tend to "telegraph" imperfections in the surface of the substrate such as bumps, dimples, or reinforcing fiber patterns.
What is needed in this art is a method of coating automobile body parts which would eliminate the need for having a coating process in an OEM assembly plant. The coated parts would be assembled directly onto an automobile chassis. There is also a need in this art for a way of producing glamour coating finishes on body parts wherein the body parts comprise various materials other than metal.